Molecular response of Chironomus riparius to antibiotics

Antibiotics, like other pharmaceuticals, are continuously released into the environment as a result of human activities. Although designed to target harmful bacteria, they can also affect non-target organisms in aquatic ecosystems. Standard toxicological tests often fail to detect the subtle or long term antibiotic-induced effects, but newer methods are providing valuable insights into the molecular pathways and physiological responses they affect. Chironomus riparius, a dipteran with aquatic larvae, is widely used in toxicological testing due to its sensitivity to various toxicants. However, little is known about the molecular effects of antibiotics on this species. This study investigated the gene expression profile of C. riparius in response to antibiotics from three classes - aminoglycosides, fluoroquinolones and penicillin. Fourth instar larvae were exposed to concentrations of 0.001, 0.1 and 10 mg/L for 24 and 72 h. The expression of genes involved in hormonal regulation, detoxification, stress response and DNA repair was analysed. The results showed that all antibiotics altered mRNA levels, with three of the four (amoxicillin, neomycin and levofloxacin) downregulating genes at 24 h and upregulating them at 72 h. Genes affected by gentamicin showed the opposite trend. These transcriptional changes in response to different antibiotics highlight the complexity of the regulatory mechanisms involved in development, detoxification, stress response and DNA repair in aquatic insects. Further research is needed to better understand the molecular effects of antibiotics on this species.